Liz Cheney, the eldest daughter of former Vice President Dick Cheney, announced on Tuesday that she will challenge Wyoming Sen. Michael B. Enzi next year in the Republican primary.

Cheney's decision sets up what will undoubtedly be a spirited primary with Enzi, 69, who confirmed in a statement on Tuesday that he will indeed run for a fourth term.

"Over the last several years citizens across our great state have urged me to consider running for the Senate in 2014," Cheney said in a video announcing her plans. "As I've traveled to every corner of Wyoming, seeing old friends and meeting new, I've been honored to have the chance to speak with so many of you about your concerns, your fears and your hopes for the future. ... Today I am launching my candidacy for the United States Senate."

Enzi responded to the news saying, "She said that if I ran, she wasn't going to run. ... I thought we were friends," according to an ABC News reporter.

This is the biggest political news to come out of the Cowboy State in recent memory, as its strong Republican tilt has provided few intriguing federal races. But even a costly primary is unlikely to affect the outcome of the general election — one of these two Republicans will almost surely win.

Speculation about a potential Cheney bid for office has been rampant since she moved to Wyoming last year. Cheney, 46, has been a steady presence on the political circuit in the state, and the New York Times reported recently that her father — a former congressman from Wyoming — has at times been by her side.

Not long before Cheney's announcement, Enzi put out a statement making it clear that he would be running.

"I intend to run for re-election for Wyoming's Senate seat in 2014," Enzi said in a statement. "When I announce formally, I will let everyone know that date in the future. In the meantime, I will do the job I was already elected to do. My trips to Wyoming almost weekly, the public listening sessions, the groups I meet with and speak to, working behind the scenes — this is what I have been doing since I was elected and this is what needs to be done."

Enzi reported raising $171,000 from April through June, and he ended the second quarter with $488,000 in cash on hand.

The senator already has the support of at least one of his colleagues: fellow Wyoming GOP Sen. John Barrasso.

"Mike Enzi is a friend, a mentor and is a tremendous U.S. Senator, and I plan to support his reelection," Barrasso said.